The present invention relates to a bar code reader for reading bar codes printed on packages or labels of goods, and more particularly to a separate-type bar code reader comprising a main body and a sub-body detachably mounted on the main body for use as a stationary bar code reader or a hand-held bar code reader.
In recent years, point-of-sale (POS) systems have been in increasing use in department stores and supermarkets so that efficiency in entering information about sales management and products has been improving.
A POS system comprises a bar code reader for reading bar codes attached to products by scanning them with a laser light beam for conversion to a form of information suitable for computational processing, a computer for processing the resulting information, and an electronic cash register coupled between the reader and the computer for outputting information for the customer.
Bar-code readers include the stationary type which requires the goods to be moved relative to the reader, the hand-held type. The hand-held type includes the touch type, the pen type, the gun type, etc., which can be moved relative to the goods. The stationary bar code reader or the hand-held bar code reader is used according to the size and weight of the goods.
In shops that deal in a wide variety of goods, however, it is uneconomical to equip both types. Therefore, a device which can be used as a stationary type or a hand-held type is desired.
Conventional bar code readers are described below.
FIG. 1A is a perspective view illustrating the interior of a conventional stationary-type bar code reader and FIG. 1B is its side view. As shown, the stationary reader includes an optical unit 4 and a recognition unit 5. The optical unit 4 has the following functions: a bar code scanning function in which outgoing light from a light-beam-producing unit 8a, comprised of a light source 6 formed of, for example, a laser diode and a beam shaping lens 7, is reflected by plane mirrors 9a and 9b to a rotating polygonal mirror 10a and the reflected light from the polygonal mirror 10a is then reflected by scanning-pattern-forming mirrors 11a to 11f to produce light beams which scan a bar code 20a of a product 2a at different angles through a reading window 12a; and a photoelectric conversion function of gathering reflected light from the bar code 20a on the product 2a through the polygonal mirror 10a and the condenser lens 13 and receiving it with an optical sensor 14a for conversion to an electrical signal.
By way of example, the polygonal mirror 10a has six reflecting surfaces and makes six scans per rotation. The reflecting surfaces of the mirror are formed vertically at different angles to produce scanning beams in different directions. The polygonal mirror 10a is rotated by a motor M1. The motor M1, the light source 6 and the optical sensor 14a are driven by a control unit 15.
The recognition unit 5 recognizes an electrical signal from the optical sensor 14a as a bar code signal through an analog to digital converter (not shown) and a demodulator (not shown). The optical unit 4 and the recognition unit 5 are housed in a casing 16a.
The bar code 20a is formed of alternate black and white printed stripes of different widths, as shown in FIG. 2, and a character, a digit, a symbol or the like is represented by the permutation of a predetermined number of stripes.
When the product 2a is moved over the reading window 12a with the bar code 20a set downward while the scanning beams emerge from the reading window 12a under the control of the control unit 15 as shown in FIGS. 1A, and 1B, the bar code is scanned by the beams and recognized as data by the recognition unit 5 after conversion of the reflected light therefrom to an electrical signal by the optical sensor 14a.
There is another type of stationary-type bar code reader in which the recognition unit is housed in a separate casing.
The stationary-type bar code reader is used where a product 2a is so small that an operator can move it over the reading window 12a with one hand and the reader can read the bar code correctly irrespective of its orientation. That is, the scanning-pattern-forming mirrors 11a to 11f enable the bar code 20a of the product 2a to be read irrespective of its orientation.
FIG. 3 is a side view of a gun-type bar code reader. As shown, the gun-type bar code reader comprises a light-producing unit 8b consisting of a light source 6a of a laser diode and a beam-shaping lens 7a, a plane mirror 9c, a polygonal mirror 10b driven by a motor M2, a scanning window 18a, a condenser lens 13a and an optical sensor 14b.
As indicated by the solid arrows and the broken arrows, outgoing light from the light outputting unit 8b is reflected by the plane mirror 9c toward the polygonal mirror 10b and then radiated from the scanning window 18a to the outside as scanning beams. By putting the scanning window close to the bar code 20a printed on a product 2a, the bar code is scanned by the scanning beams. The reflected light from the bar code is gathered by the condenser lens 13a via the polygonal mirror 10b and then received by the optical sensor 14b for conversion to an electrical signal which is in turn applied to the external recognition unit (not shown).
The gun type reader 1a is used when the stationary reader 1 is difficult to use, e.g., where a product 2a is large or heavy or where there are a number of products even if they are small. With the gun type reader, however, since the scanning beams are oriented in one direction, the bar code 20a must be read in this direction.
Problems with the conventional bar code readers are summarized as follows. The stationary type reader in which an operator needs to move a product over the scanning window is difficult to operate with large or heavy products is and reduce the operator's efficiency. In such a case, the operator has to enter product information through the keyboard of an electronic cash register, or uses an additionally equipped hand reader such as the gun type reader recited above. Having a stationary-type reader as well as hand-held reader is uneconomical.